Index: Lib/difflib.py
===================================================================
--- Lib/difflib.py	(revision 64497)
+++ Lib/difflib.py	(working copy)
@@ -203,11 +203,10 @@
         # isbjunk
         #      for x in b, isbjunk(x) == isjunk(x) but much faster;
         #      it's really the has_key method of a hidden dict.
-        #      DOES NOT WORK for x in a!
         # isbpopular
         #      for x in b, isbpopular(x) is true iff b is reasonably long
         #      (at least 200 elements) and x accounts for more than 1% of
-        #      its elements.  DOES NOT WORK for x in a!
+        #      its elements.
 
         self.isjunk = isjunk
         self.a = self.b = None
@@ -344,8 +343,8 @@
         # lot of junk in the sequence, the number of *unique* junk
         # elements is probably small.  So the memory burden of keeping
         # this dict alive is likely trivial compared to the size of b2j.
-        self.isbjunk = junkdict.has_key
-        self.isbpopular = populardict.has_key
+        self.isbjunk = junkdict.__contains__
+        self.isbpopular = populardict.__contains__
 
     def find_longest_match(self, alo, ahi, blo, bhi):
         """Find longest matching block in a[alo:ahi] and b[blo:bhi].
@@ -654,9 +653,7 @@
         >>> s.real_quick_ratio()
         1.0
         """
-
-        matches = reduce(lambda sum, triple: sum + triple[-1],
-                         self.get_matching_blocks(), 0)
+        matches = sum(triple[-1] for triple in self.get_matching_blocks())
         return _calculate_ratio(matches, len(self.a) + len(self.b))
 
     def quick_ratio(self):
@@ -677,12 +674,9 @@
         # avail[x] is the number of times x appears in 'b' less the
         # number of times we've seen it in 'a' so far ... kinda
         avail = {}
-        availhas, matches = avail.has_key, 0
+        matches = 0
         for elt in self.a:
-            if availhas(elt):
-                numb = avail[elt]
-            else:
-                numb = fullbcount.get(elt, 0)
+            numb = avail.get(elt, fullbcount.get(elt, 0))
             avail[elt] = numb - 1
             if numb > 0:
                 matches = matches + 1